Many types of fasteners are used to removably attach one panel to another. Often, sheet metal screws or machine screws, with or without nuts, are used for these tasks. Although these screw type fasteners will securely fasten one panel to another and are readily unfastened, they are inadequate for many applications. For instance, screw type fasteners take too long to assemble and disassemble, require relatively precise tolerances in panel fit, and are subject to cross-threading, stripping, and under- or over-tightening. There is a need for fasteners that are quick and easy to use, and that positively engage. This is particularly true in light industrial applications such as the computer industry, where it is desired to attach various loose-fitting components and covers in a positive secure fashion that allows such covers and components to be easily installed and removed.
Quarter-turn latches are used for latching a variety of cabinets, doors and other enclosures. It has been suggested to construct a quarter-turn fastener as shown in FIG. 1. A bolt 1 has a disk-shaped head 2 and a cylindrical shank 3. Two projecting keys 4, 5 project radially outward from the shank 3 opposite one another. A keyhole 6, shown in FIG. 2, is made in each panel 10, 11 to be adjoined. The keyhole 6 consists of a circular hole 7 with two radially extending rectangular slots 8, 9 opposite one another. In operation, the top panel 10 is placed over the bottom panel 11 with the keyhole in each panel aligned. The bolt 1 is guided through the panels 10, 11 and the keys 4, 5 simultaneously pass through the slots 8, 9.
The bolt is twisted 90.degree., placing the keys 4, 5 in the positions 12, 13 shown by dotted lines in FIG. 2, effectively locking the panels 10, 11 together. A coil spring 14 coaxially surrounds the shank 3 and is compressed between the bolt head 2 and the top panel 10. The compressed spring 14 pulls the keys 4, 5 against the underside of the bottom panel 11, holding the bolt 1 in position by friction. Thus, the spring 14 provides a compressive biasing force that pulls the panels 10, 11 together for positive engagement and to avoid rattles.
Drawbacks exist with many quarter-turn latches. For instance, they can be susceptible to operator error. Without positive engagement, the operator can turn the bolt too far, or not far enough. The bolt can rotate to the unlocked position due to vibration. In addition, the coil spring adds purchase and assembly costs, and can be lost. Consequently, there is a need for a quarter-turn fastener which is simple, inexpensive, requires a minimum number of parts, and provides positive engagement.